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DSM-V: Applying the Medical Model

DSM-V: Applying the Medical Model

In “Changes in Psychiatric Diagnosis” (Psychiatric Times, November 2008, page 14) Michael First relates the sad fact that the reorganization of DSM is still without formal guidelines and continues to be subject to the vicissitudes of groupthink and vocal constituencies. He relates that he and Allen Frances envisioned the application of biologically based diagnostic criteria when summarizing the work of DSM-IV, but complains that no criteria are forthcoming as yet.

At least 2 diagnostic groups, catatonia and melancholia, are established within the medical model of diagnosis as the identification of a syndrome by symptoms, signs, and course; verified by laboratory tests; and validated by treatment response. Both syndromes have been described in Psychiatric Times.1-4

Melancholia is a disturbance in mood characterized by depression, mania, or the combination, often of acute onset, with severe vegetative abnormalities (insomnia, anorexia, weight loss, etc) and motor disturbance (lassitude, inactivity, agitation, pacing). The condition is accompanied by a severe disturbance in cortisol metabolism that is measurable by hypercortisolemia and abnormal suppression of cortisol synthesis with corticosteroids (eg, the dexamethasone suppression test), which verifies the psychiatric diagnosis.5

Remarkably, the manifestations of melancholia respond to adequate treatment with tricyclic antidepressants (TCAs) and, when these fail, to electroconvulsive therapy (ECT). Validation by treatment response is a feature of the medical model and is clearly applicable to this psychiatric illness. Indeed, rates of remission of melancholic depression treated with ECT exceed 85%—life-saving identification that justifies the classification of melancholia as an independent syndrome.

Some DSM-identified depressive subtypes, such as psychotic depression, abnormal bereavement, and puerperal depression, fulfill the criteria for a diagnosis of melancholia. The incidence of vegetative signs, abnormal cortisol metabolism, and response to TCAs and ECT clearly place these subtypes within the category of melancholia.

The second formulation of a definable disorder that meets the medical model of diagnosis is catatonia.6 The inclusion of catatonia by Kraepelin and Bleuler as a type of schizophrenia was an error of heroic proportions; it was sustained in DSM and the International Classification of Diseases despite extensive contrary evidence. Catatonia is a motor dysregulation syndrome that is associated with mental changes, and it has roots in mood, seizure, medical, and toxic disorders. It is only rarely a type of schizophrenia. (Indeed, the present DSM equation that catatonia is schizophrenia that must be treated with antipsychotic drugs and not with benzodiazepines and ECT has done a gross disservice to many patients described in case reports cited in the literature.)

Catatonia is identified by the presence of 2 or more motor abnormalities (mutism, negativism, posturing, rigidity, stereotypy, staring, etc) for 24 hours or longer. Its diagnosis is verified by the rapid response to intravenous lorazepam and is validated by symptom remission with either high doses of lorazepam or ECT. Catatonia is recognized in a malignant form and as the neuroleptic malignant and toxic serotonin syndromes. Self-injurious behavior is a feature of autism spectrum disorders and mental retardation that responds to treatment for catatonia. The stereotypies of Tourette syndrome and obsessive-compulsive disorder are best explored as catatonia.

A small nudge to understanding catatonia as a distinct syndrome was made in DSM-IV by the inclusion of the category of 293.89—catatonia secondary to a medical disorder. A more important delineation of catatonia as a syndrome of its own, similar to delirium and dementia in the present classifications, is a full step forward in the dream envisioned by Frances and First in their hopes for the future after DSM-IV.

While these formulations of melancholia and catatonia are small steps in the development of a verifiable and medical classification, they warrant consideration in DSM-V. Separation of melancholia from non-melancholic mood disorders will do much to improve diagnosis, treatment, and the inadequacies of large clinical trials (eg, STAR*D, STEP-BD) that seem unable to define the application and efficacy of some highly touted medication treatments.

Michael First’s call for applying the medical model to DSM-V categorization is to be applauded, and these 2 syndromes are well-documented starting points.

References

References

1. Fink M. Catatonia and NMS: Recognition and treatment. Psychiatr Times. 1997;14:42, 49.
2. Fink M. Catatonia in adolescents and children. Psychiatr Times. 2002;19(9):28-29.
3. Fink M. Treating catatonia in autism. Psychiatr Times. 2008;24(14):17, 20.
4. Fink M. Should the diagnosis of melancholia be revived? Psychiatr Times. 2006;23(7):25-26.
5. Taylor MA, Fink M. Melancholia: The Diagnosis, Pathophysiology and Treatment of Depressive Illness. New York: Cambridge University Press; 2006.
6. Fink M, Taylor MA. Catatonia: A Clinician’s Guide to Diagnosis and Treatment. New York: Cambridge University Press; 2003.

 
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